Clojurians Log v2

Hi. Just sent a PR providing a way to render a devcard inside of an iframe, isolated from the rest of the devcards and devcards system, useful to create devcards that need access to global state, for example in re-frame apps. Feedback would be very welcome. https://github.com/bhauman/devcards/pull/131

@bhauman: I changed the implementation since the last time we discussed it (a while ago): It now uses IDevcardOptions (more precisely, via create-idevcard) and it's less invasive, so for example there's a separate devcards.iframe ns now